Hemoglobin subunit theta-1 (HBQ1)
The protein contains 142 amino acids for an estimated molecular weight of 15508 Da.
No function (updated: March 4, 2015)
Protein identification was indicated in the following studies:
- Goodman and co-workers. (2013) The proteomics and interactomics of human erythrocytes. Exp Biol Med (Maywood) 238(5), 509-518.
- Lange and co-workers. (2014) Annotating N termini for the human proteome project: N termini and Nα-acetylation status differentiate stable cleaved protein species from degradation remnants in the human erythrocyte proteome. J Proteome Res. 13(4), 2028-2044.
- Hegedűs and co-workers. (2015) Inconsistencies in the red blood cell membrane proteome analysis: generation of a database for research and diagnostic applications. Database (Oxford) 1-8.
- Bryk and co-workers. (2017) Quantitative Analysis of Human Red Blood Cell Proteome. J Proteome Res. 16(8), 2752-2761.
- D'Alessandro and co-workers. (2017) Red blood cell proteomics update: is there more to discover? Blood Transfus. 15(2), 182-187.
- Chu and co-workers. (2018) Quantitative mass spectrometry of human reticulocytes reveal proteome-wide modifications during maturation. Br J Haematol. 180(1), 118-133.
Methods
The following articles were analysed to gather the proteome content of erythrocytes.
The gene or protein list provided in the studies were processed using the ID mapping API of Uniprot in September 2018. The number of proteins identified and mapped without ambiguity in these studies is indicated below.
Only Swiss-Prot entries (reviewed) were considered for protein evidence assignation.
| Publication | Identification 1 | Uniprot mapping 2 | Not mapped / Obsolete | TrEMBL | Swiss-Prot |
|---|---|---|---|---|---|
| Goodman (2013) | 2289 (gene list) | 2278 | 53 | 20599 | 2269 |
| Lange (2014) | 1234 | 1234 | 7 | 28 | 1224 |
| Hegedus (2015) | 2638 | 2622 | 0 | 235 | 2387 |
| Wilson (2016) | 1658 | 1528 | 170 | 291 | 1068 |
| d'Alessandro (2017) | 1826 | 1817 | 2 | 0 | 1815 |
| Bryk (2017) | 2090 | 2060 | 10 | 108 | 1942 |
| Chu (2018) | 1853 | 1804 | 55 | 362 | 1387 |
1 as available in the article and/or in supplementary material
2 uniprot mapping returns all protein isoforms as one entry
The compilation of older studies can be retrieved from the Red Blood Cell Collection database.
The data and differentiation stages presented below come from the proteomic study and analysis performed by our partners of the GReX consortium, more details are available in their published work.
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Biological Process
Cellular oxidant detoxification
Hydrogen peroxide catabolic process
Oxygen transport
Protein heterooligomerization
Molecular Function
Heme binding
Iron ion binding
Organic acid binding
Oxygen binding
Oxygen carrier activity
The reference OMIM entry for this protein is 142240
Hemoglobin--theta-1 locus; hbq1
Studying the orangutan, Marks et al. (1986) discovered a 'new' functional globin gene in the alpha cluster (16p13.33-p13.11). The orangutan gene, called theta-1, has all the sequence elements necessary for an expressible, protein-coding gene although its actual expression and function are unknown. Theta-1 in the orangutan is located 3 kb downstream from the adult alpha-1 gene. The putative polypeptide for which it codes is 141 amino acids long, identical to the alpha and zeta globins. It differs from orangutan alpha globin (by 55 aa) as much as human alpha and zeta differ (by 59 aa), suggesting an ancient origin of the theta-1 gene. Marks et al. (1986) cloned the theta-1 gene in man and found map arrangements similar to those in orangutan and baboon. Peschle et al. (1985) found as yet uncharacterized globin polypeptides in early stages of human embryo development. The theta-1 gene may be expressed very early in embryonic life, perhaps sometime before 5 weeks. Clegg (1987) concluded that the predicted amino acid sequence of the theta-1 gene suggests that any 'globin' product is likely to be nonviable because of seriously deleterious amino acid replacements. Some of these amino acid changes are shared by horse, rabbit, and primate, indicating that they predate the mammalian radiation, and that if indeed any of these genes are still functional, they are unlikely to be making hemoglobin. Leung et al. (1987), however, demonstrated theta-globin messenger RNA in human fetal erythroid tissue but not in adult erythroid or other nonerythroid tissue; furthermore, they could detect theta-globin mRNA in significant amounts in a human erythroleukemic cell line. Surprisingly, the promoter sequence of theta-globin did not correspond to the CCAAT and ATA box sequences of the gene, but rather was found to lie in the adjacent GC-rich sequence. This type of promoter is reminiscent of that found in housekeeping genes such as ADA (608958) and HPRT (308000). Hsu et al. (1988) reported that both theta-1 genes are split into 3 exons with the potential to code for a 141-amino acid polypeptide. They presented the complete DNA sequence of a cloned theta-1 gene of man, and showed that it contained no apparent defects that would abolish its expression. Furthermore, they showed that the gene is transcribed in an erythroleukemia cell line. The findings supported a transcriptionally active role for the gene and a functional role for the peptide in specific cells, possibly those of early erythroid tissue. Fei et al. (1988) described 2 different theta-1 globin gene deletions in blacks. No hematologic alterations were associated. Utsch et al. (2001) diagrammed the position of the globin genes on chromosome 16p as follows: 5-prime-zeta--pseudo-zeta--pseudo-alpha--alpha-1--alpha-2--theta-1-3-prime. Utsch et al. (2001) cited unpublished evidence that a theta-2 locus is on chromosome 10. ... More on the omim web site
Feb. 2, 2018: Protein entry updated
Automatic update: Uniprot description updated
Dec. 19, 2017: Protein entry updated
Automatic update: Uniprot description updated
Nov. 23, 2017: Protein entry updated
Automatic update: Uniprot description updated
June 20, 2017: Protein entry updated
Automatic update: comparative model was added.
March 16, 2016: Protein entry updated
Automatic update: OMIM entry 142240 was added.